Chapter 2 · Class 6 ICSE · MCQ Test
HCF & LCM MCQ Test — Class 6 ICSE
Practice 10 multiple-choice questions with instant answer reveal and explanations.
HCF & LCM — MCQ Questions
1Which of the following is a prime number?
Show Answer+
Answer: 29
Hint: A prime number has exactly two factors: 1 and itself.
Solution:
Check each number: 15 = 3 × 5, 21 = 3 × 7, 35 = 5 × 7.
29 has no factors other than 1 and 29, so it is prime.
2Find the prime factorization of 36.
Show Answer+
Answer: 2² × 3²
Hint: Break 36 into its smallest prime factors by dividing repeatedly.
Solution:
Divide by primes: — 36 = 2 × 18 = 2 × 2 × 9 = 2 × 2 × 3 × 3
Prime factorization: — 36 = 2² × 3²
3Find the HCF of 12 and 18.
Show Answer+
Answer: 6
Hint: List the factors of both numbers and find the greatest common one.
Solution:
Factors of 12: 1, 2, 3, 4, 6, 12. Factors of 18: 1, 2, 3, 6, 9, 18.
Common factors: 1, 2, 3, 6. Greatest = 6. — HCF(12, 18) = 6
4Find the LCM of 4 and 6.
Show Answer+
Answer: 12
Hint: LCM is the smallest number that is a multiple of both 4 and 6.
Solution:
Multiples of 4: 4, 8, 12, 16, ... Multiples of 6: 6, 12, 18, ...
Smallest common multiple: — LCM(4, 6) = 12
5Is 1 a prime number?
Show Answer+
Answer: No
Hint: A prime number must have exactly TWO distinct factors.
Solution:
1 has only one factor: itself (1).
Since a prime number must have exactly two distinct factors (1 and itself), 1 is NOT prime.
6Which of the following is a composite number?
Show Answer+
Answer: 15
Hint: A composite number has more than two factors.
Solution:
15 = 3 × 5, so it has factors: 1, 3, 5, 15 (more than 2 factors).
7, 11, and 23 are all prime (exactly 2 factors each).
7Find the HCF of 8 and 12 using the prime factorization method.
Show Answer+
Answer: 4
Hint: Write the prime factorization of both, then multiply the common prime factors with the lowest powers.
Solution:
8 = 2³ and 12 = 2² × 3.
Common prime factor: 2 with lowest power 2. — HCF = 2² = 4
8Find the LCM of 5 and 7.
Show Answer+
Answer: 35
Hint: When two numbers are co-prime (no common factor except 1), their LCM is their product.
Solution:
5 and 7 are both prime, so they share no common factor except 1.
LCM: — LCM(5, 7) = 5 × 7 = 35
9Express 48 as a product of its prime factors.
Show Answer+
Answer: 2⁴ × 3
Hint: Keep dividing 48 by 2 until you cannot, then try the next prime.
Solution:
48 ÷ 2 = 24, 24 ÷ 2 = 12, 12 ÷ 2 = 6, 6 ÷ 2 = 3, 3 ÷ 3 = 1.
Prime factorization: — 48 = 2⁴ × 3
10What is the HCF of two co-prime numbers?
Show Answer+
Answer: 1
Hint: Co-prime numbers share no common factor other than 1.
Solution:
Co-prime numbers have only 1 as their common factor.
Therefore, HCF of co-prime numbers = 1.
Want more questions?
Practice 60+ questions with AI-powered doubt clearing and step-by-step solutions.
Tips for HCF & LCM MCQs
- 1Read each question carefully and identify what is being asked before looking at the options.
- 2Try to solve the problem mentally or on paper first, then match your answer with the options.
- 3Use elimination — rule out clearly wrong options to improve your chances even when unsure.
- 4Check units, signs, and edge cases — these are common traps in HCF & LCM MCQs.
- 5Review your mistakes after completing the test to build lasting understanding.
Master HCF & LCM on SparkEd
Go beyond MCQs. Practice at three difficulty levels with instant feedback, solutions, and an AI coach to clear every doubt.
Start PractisingSparkEd Maths offers free MCQ tests for Class 1-10 across 7 education boards. All questions are aligned to the 2025-26 syllabus with step-by-step solutions and AI-powered doubt clearing.